Technical Field
The present disclosure generally relates to electronic circuits and, more specifically, to circuits containing elements storing data in non-volatile fashion. The present disclosure, for example, may apply to integrated electronic systems (System On Chip).
Description of the Related Art
As soon as an electronic system manipulates digital data, the data are typically at least temporarily stored in elements of the electronic circuits. These typically are RAM-type volatile storage elements, or registers or flip-flops storing binary data when they are being processed by the electronic circuit.
In principle, these data disappear when the integrated circuit is no longer powered. Actually, they do not really disappear, but the state that they represent is no longer reliable on restarting of the circuit.
In circuits manipulating digital data considered as secret, that is, that can only be accessed by authorized users or circuits, it should be ascertained that the data volatilely manipulated by an integrated circuit are no longer accessible in storage elements for applications other than authorized applications. Areas of the RAM assigned to such applications are thus generally reserved. Such a reservation is however dynamic, that is, it disappears at the circuit switching down or resetting. It should thus be ascertained that the data contained in previously-reserved areas are no longer accessible, for example, after a restarting of the electronic system. Indeed, even if the circuit switching down makes the data non-reliable, they are capable of containing, even partially, secret information. A first step of resetting the volatile memory elements is thus provided at the switching up of an electronic circuit, by erasing the memory at the switching up. Such a technique takes time.